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Romanchuk A, Trigub A, Plakhova T, Kuzenkova A, Svetogorov R, Kvashnina K, Kalmykov S. Effective coordination numbers from EXAFS: general approaches for lanthanide and actinide dioxides. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:288-294. [PMID: 35254290 PMCID: PMC8900841 DOI: 10.1107/s160057752101300x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/07/2021] [Indexed: 06/01/2023]
Abstract
Extended X-ray absorption fine structure (EXAFS) is a comprehensive and usable method for characterizing the structures of various materials, including radioactive and nuclear materials. Unceasing discussions about the interpretation of EXAFS results for actinide nanoparticles (NPs) or colloids were still present during the last decade. In this study, new experimental data for PuO2 and CeO2 NPs with different average sizes were compared with published data on AnO2 NPs that highlight the best fit and interpretation of the structural data. In terms of the structure, PuO2, CeO2, ThO2, and UO2 NPs exhibit similar behaviors. Only ThO2 NPs have a more disordered and even partly amorphous structure, which results in EXAFS characteristics. The proposed new core-shell model for NPs with calculated effective coordination number perfectly fits the results of the variations in a metal-metal shell with a decrease in NP size.
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Affiliation(s)
- Anna Romanchuk
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
| | - Alexander Trigub
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
- National Research Centre ‘Kurchatov Institute’, Pl. Kurchatova 1, Moscow 123182, Russian Federation
| | - Tatiana Plakhova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
| | - Anastasiia Kuzenkova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
| | - Roman Svetogorov
- National Research Centre ‘Kurchatov Institute’, Pl. Kurchatova 1, Moscow 123182, Russian Federation
| | - Kristina Kvashnina
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
- The Rossendorf Beamline at ESRF – The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314 Dresden, Germany
| | - Stepan Kalmykov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Bld. 3, Moscow 119991, Russian Federation
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Li P, Goswami S, Otake KI, Wang X, Chen Z, Hanna SL, Farha OK. Stabilization of an Unprecedented Hexanuclear Secondary Building Unit in a Thorium-Based Metal–Organic Framework. Inorg Chem 2019; 58:3586-3590. [DOI: 10.1021/acs.inorgchem.8b03511] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Peng Li
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Subhadip Goswami
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ken-ichi Otake
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xingjie Wang
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China
| | - Zhijie Chen
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Sylvia L. Hanna
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Omar K. Farha
- Department of Chemistry and International Institute of Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Abstract
Abstract
The solubility and redox behavior of hydrous Pu(IV) oxide was comprehensively investigated by an experimental multi-method approach as a function of different redox conditions in 0.1 M NaCl solutions, allowing a detailed characterization of Pu(IV) and Pu(III) solubility and solid phase stability in these systems. Samples were prepared at ~3≤pHm≤~6 (pHm=–log
m
H
+
)
${{\text{m}}_{{{\text{H}}^{\text{ + }}}}})$
and ~8≤pHm≤~13 at T=(22±2)°C under Ar atmosphere. No redox buffer was used in one set of samples, whereas mildly and strongly reducing redox conditions were buffered in two series with hydroquinone or SnCl2, respectively, resulting in (pe+pHm)=(9.5±1) and (2±1). XRD, XANES and EXAFS confirmed the predominance of Pu(IV) and the nanocrystalline character of the original, aged PuO2(ncr,hyd) solid phase used as a starting material. Rietveld analysis of the XRD data indicated an average crystal (domain) size of (4±1) nm with a mean cell parameter of (5.405±0.005) Å. The solubility constant of this solid phase was determined as log
∗
K
°
s
,
0
$^ * K{^\circ _{{\text{s}},0}}$
=–(58.1±0.3) combining solubility data in acidic conditions and redox speciation by solvent extraction and CE–SF–ICP–MS. This value is in excellent agreement with the current thermodynamic selection in the NEA-TDB. Synchrotron-based in-situ XRD, XANES and EXAFS indicate that PuO2(ncr,hyd) is the solid phase controlling the solubility of Pu in hydroquinone buffered samples. Under these redox conditions and ~8≤pHm≤~13, the solubility of Pu is very low (~10−10.5 m) and pH-independent. This is consistent with the solubility equilibrium PuO2(am,hyd)+2H2O(l)⇔ Pu(OH)4(aq). Although in-situ XRD unequivocally shows the predominance of PuO2 in Sn(II)-buffered systems, XANES analyses indicate a significant contribution of Pu(III) (30±5%) in the solid phases controlling the solubility of Pu at (pe+pHm)=(2±1). For this system, EXAFS shows a systematic shortening of Pu–O and Pu–Pu distances compared to the starting Pu material and hydroquinone-buffered systems. The solubility of Pu remains very low (~10−10.5 m) at pHm>9, but shows a very large scattering (~10−9–10−10.5 m) at pHm=8. Experimental observations collected in Sn(II) buffered systems can be explained by the co-existence of both PuO2(ncr,hyd) and Pu(OH)3(am) solid phases, but also by assuming the formation of a sub-stoichiometric PuO2−x
(s) phase. This extensive study provides robust upper limits for Pu solubility in alkaline, mildly to strongly reducing conditions relevant in the context of nuclear waste disposal. The potential role of Pu(III) in the solid phases controlling the solubility of Pu under these conditions is analysed and discussed in view of the current NEA-TDB thermodynamic selection, which supports the predominance of PuO2(am,hyd) and constrains the formation of Pu(OH)3(am) at pHm>8 outside the stability field of water.
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Walther C, Denecke MA. Actinide Colloids and Particles of Environmental Concern. Chem Rev 2013; 113:995-1015. [DOI: 10.1021/cr300343c] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Clemens Walther
- Institute for Radioecology and
Radiation Protection, Leibniz University Hannover, Herrenhäuser Strasse 2, D-30419 Hannover, Germany
| | - Melissa A. Denecke
- Institute for Nuclear Waste
Disposal, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany
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Knope KE, Soderholm L. Solution and Solid-State Structural Chemistry of Actinide Hydrates and Their Hydrolysis and Condensation Products. Chem Rev 2012; 113:944-94. [DOI: 10.1021/cr300212f] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Karah E. Knope
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439,
United States
| | - L. Soderholm
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439,
United States
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Torapava N, Radkevich A, Persson I, Davydov D, Eriksson L. Formation of a heteronuclear hydrolysis complex in the ThIV–FeIII system. Dalton Trans 2012; 41:4451-9. [DOI: 10.1039/c2dt30058c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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